The invention relates to circuitry for an emissions analyzer which analyzes the exhaust gas stream of an internal combustion engine, and more particularly to an automatic biasing control circuit for an infrared detector utilized in an emissions analyzer.
The circuitry embodiment of the invention described herein is used in an emissions analyzer which analyzes the exhaust gas stream of an internal combustion engine. Specifically, the described circuitry optimizes the constant current bias on an infrared detector. Heretofore, the practice has been to bias the infrared detector of an analyzer either from a constant voltage source such as .+-.15 VDC, with the detector in series with a fixed resistor, or from a constant current source, in which case a trimpot current adjustment is required due to wide variations in the resistance of commercially available detectors.
The present invention circumvents these requirements by adjusting the detector current automatically without the need for manual trimpot adjustments.
It is therefore an object of the present invention to provide an improved circuit for biasing the emissions detector of an exhaust gas analyzer.
It is a further object of the present invention to provide an automatic biasing control circuit for a radiant energy detector.